Unit comprising a collection tank

Abstract

The invention relates to a unit (1) and a method, comprising a collection tank (2), which has an inlet (3) for a mixture of seal oil and refrigerant, also an outlet (10) for seal oil, also an additional tank (6) which is designed to collect refrigerant and is fluidically connected to the collection tank (2).

Description

[0001] Description

[0002] Facility with a collection tank

[0003] The invention relates to a device comprising a collecting tank which has a supply for a mixture of sealing oil and refrigerant and further comprises a discharge for sealing oil.

[0004] Furthermore, the invention relates to a method for collecting a sealing oil and a refrigerant, wherein in one step a mixture of sealing oil and refrigerant is fed into a collecting tank.

[0005] A turbo compressor, which can also be configured as a heat pump, is used to compress a process gas in a process engineering process. In the case of a heat pump, the process gas is also referred to as the refrigerant.

[0006] The turbo compressor has a rotor which is supported by bearings outside a housing which encloses the rotor. Since there is relative movement between the rotor and the housing when the turbo compressor is in operation, a gap must be maintained at the point where the rotor shaft emerges from the inside of the housing to the outside. The gap must be bridged with a shaft seal in order to prevent any leakage of process gas from the inside of the turbo compressor to the outside, or at least to keep it acceptably small. If the process gas is flammable, toxic and / or environmentally hazardous, the demands placed on the shaft seal in terms of its sealing effect are high. It is known to use oil-lubricated plain bearings, in particular oil-lubricated tilting pad plain bearings, for the bearings.The design of the plain bearings is matched to the operating speed and the rotor dynamics of the rotor, with the shaft seal and the bearing being arranged directly adjacent to each other on the shaft.

[0007] In a cyclic process, such as a refrigeration cycle, high demands are placed on the shaft seal. Leakage of the process gas from the turbo compressor must be kept to a minimum. If, for example, the shaft seal is designed as a liquid seal which is sealed with a barrier oil, the barrier oil must be selected to be chemically compatible with the refrigerant. Traditionally, the barrier oil is also used as the lubricating oil for the bearings, so the turbo compressor is supplied by a combined lubricating / barrier oil system, whereby the barrier oil must also be suitable for lubricating and cooling the bearings. The barrier oil therefore has to meet a wide range of requirements. For example, mineral oil may be unsuitable as the barrier oil for lubricating the bearings and locking the shaft seals because the mineral oil may not be compatible with the refrigerant used in the refrigeration process.Special synthetic oils can provide a remedy, but they are highly hygroscopic and therefore must not be brought into contact with the humidity of the outside atmosphere.

[0008] Thus, the barrier oil in oil-lubricated mechanical seals in refrigerant compressors can absorb refrigerant during operation. The refrigerant must be returned to the refrigerant circuit in a gaseous state through an extraction process. The problem here is that the extraction process must take place under almost atmospheric conditions, since the sealing system is open to the atmosphere on one side.

[0009] In conventional seals, this atmospheric side is open and is directed into the environment. Thus, emissions were always present with such seals. Therefore, attempts were made to keep this leakage as small as possible.

[0010] Against this background, the invention has set itself the task of specifying a device in which emission of the refrigerant is prevented.

[0011] This object is achieved by a device comprising a collecting tank which has a supply for a mixture of sealing oil and refrigerant, further comprises a discharge for sealing oil, further comprises an additional tank which is designed to collect refrigerant and is fluidically connected to the collecting tank.

[0012] Furthermore, the object is also achieved by a method for collecting a barrier oil and a refrigerant, comprising the steps:

[0013] -Feeding a mixture of sealing oil and refrigerant into a collection tank;

[0014] -Collecting the refrigerant escaping from the sealing oil in an additional tank.

[0015] The invention makes it possible to virtually prevent the emission of the refrigerant by using an additional tank which is designed to collect the refrigerant and which is designed with a variable volume.

[0016] A key concept of the invention is that the auxiliary tank has a bladder that collects the refrigerant and whose volume is variable. This allows the refrigerant to be exchanged between the auxiliary tank and the collection tank during operation.

[0017] The bladder, which can also be referred to as an atmospheric tank bladder, is designed to separate the seal from atmospheric air, allowing only a minimal differential pressure to build up. This prevents the exchange of refrigerant into the environment.

[0018] The bladder, made of an elastic material, is installed in the auxiliary tank and encloses the sealing oil. When the oil is returned from the tank to the sealing oil circuit, the bladder contracts, adapting to the sealing oil volume. The cavity between the tank's inner wall and the tank bladder is then filled with air instead of refrigerant vapor, which can then breathe into the atmosphere. The advantage is that this prevents the emission of refrigerant into the environment.

[0019] Advantageous further developments are specified in the subclaims.

[0020] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which are explained in more detail in connection with the drawings.

[0021] Identical components or components with the same function are marked with the same reference symbols.

[0022] Exemplary embodiments of the invention are described below with reference to the drawings. These are not intended to represent the exemplary embodiments to scale; rather, where useful for explanation, the drawings are presented in a schematic and / or slightly distorted form. For supplements to the teachings immediately apparent in the drawings, reference is made to the relevant prior art.

[0023] It shows :

[0024] Figure 1 is a schematic representation of an embodiment of a device according to the invention

[0025] Figure 1 shows a schematic representation of an embodiment of the invention.

[0026] Figure 1 shows a device 1 comprising a collection tank 2. The collection tank 2 is designed to be filled with a mixture of sealing oil and refrigerant. The mixture of sealing oil and refrigerant originates, for example, from a turbocompressor or a heat pump in which sealing oil is used in the shaft seal. During operation, the sealing oil mixes with small amounts of refrigerant. The refrigerant is used as a process gas in the turbocompressor or heat pump.

[0027] The mixture of sealing oil and refrigerant thus created in the turbo compressor or heat pump passes through a feed line 3 into the collecting tank 2. The mixture of sealing oil and refrigerant collects in the collecting tank 2, with the refrigerant outgassing from the sealing oil over time, i.e. being separated and collecting above the sealing oil.

[0028] In Figure 1, a first filling level 4 with sealing oil is represented by the dashed line. Sealing oil can therefore collect up to this line, with the space above the dashed line then being filled with refrigerant. The two additional dashed lines above the dashed line 4 represent additional filling levels with sealing oil as examples.

[0029] The refrigerant flows through a line 5 to an additional tank 6. The line 5 establishes a fluid connection between the collection tank 2 and the additional tank 6. The line 5 is arranged at a geodetically high position.

[0030] The additional tank 6 is formed with a housing 7, within which there is a bladder 8 which is ultimately filled with refrigerant. The volume of the bladder 8 is variable so that more and more refrigerant can collect during operation. For this reason, the bladder 8 is made of an elastic material. The upper half of the illustration of the additional tank 6 shows a state of the bladder 8 in which the bladder 8 is comparatively well filled, whereas the lower half of the illustration of the additional tank 6 shows a lower filling level, which can be seen from the smaller volume of the bladder 8. The functioning of the bladder 8 can therefore be compared to a balloon, the volume of which can also change. Here, too, the volume of the bladder 8 changes depending on the operating conditions, as a result of which the amount of temporarily stored refrigerant is variable.

[0031] Such a device 1 prevents refrigerant from a turbo compressor process or heat pump process from escaping into the atmosphere.

[0032] Air is arranged between the bladder 8 and the housing 7.

[0033] A valve 9 is arranged in line 5 and is normally open when the bladder 8 is being filled. During operation, a certain amount of sealing oil is drained via a drain 10. Draining the sealing oil creates a vacuum above the filling level 4. This causes the space above the sealing oil in the collecting tank 2 to fill with refrigerant from the additional tank 6.

[0034] If the amount of refrigerant in the collection tank 2 and the additional tank 6 reaches a certain limit, the refrigerant is discharged via a vent valve 11 located in line 5. The refrigerant can then be fed back to the turbo compressor or the heat pump as a process gas. Valve 9 must remain closed when the refrigerant is discharged via the vent valve 11.

[0035] Thus, the collection tank 2 and the additional tank 6 are operated in such a way that the collection tank 2 is filled with a mixture of sealing oil and refrigerant, the refrigerant is separated from the sealing oil and collected in the additional tank 6, wherein after the sealing oil separated from the refrigerant has been discharged, the collection tank 2 is filled with refrigerant from the additional tank 6.

[0036] Since the sealing oil discharged from the collection tank 2 may still contain refrigerant, it is separated from the refrigerant in a subsequent process, which is not described in detail here.

[0037] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived by the person skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Device (1) comprising a collection tank (2) which has a supply (3) for a mixture of sealing oil and refrigerant, further comprises a discharge (10) for sealing oil, further comprises an additional tank (6) which is designed to collect refrigerant and is fluidly connected to the collection tank (2).

2. Device (1) according to claim 1, wherein the additional tank (6) has a bladder (8) made of an elastic material.

3. Device (1) according to claim 2, wherein the volume of the bladder (8) is variable.

4. Device (1) according to claim 2 or 3, wherein a housing (7) is arranged around the bladder (8), wherein air is arranged between the housing (7) and the bladder (8) and is fluidically connected to the atmosphere via a valve.

5. Device (1) according to one of the preceding claims, wherein between the collecting tank (2) and the additional tank (6) a valve (9) is arranged.

6. Device (1) according to one of the preceding claims, wherein the collecting tank (2) has a vent valve (11) which forms a fluidic connection between the refrigerant in the collecting tank (2) and an additional device.

7. A method for collecting a barrier oil and a refrigerant, comprising the steps of: -feeding a mixture of sealing oil and refrigerant into a collecting tank (2); -Collecting the refrigerant escaping from the sealing oil in an additional tank (6).

8. The method according to claim 7, wherein the collecting tank (2) is filled with refrigerant from the additional tank (6) when sealing oil is removed from the collecting tank (2) via a discharge (10).

9. Method according to claim 7 or 8, wherein between the additional tank (6) and the collecting tank (2) a valve (9) is arranged.

10. Method according to one of claims 7 to 9, wherein a vent valve (11) is arranged as a fluidic connection between the collecting tank (2) and the additional tank (6), which creates a fluidic connection between the refrigerant in the collecting tank (2) and an additional device.

11. Method according to one of claims 7 to 10, wherein the additional tank (6) is formed with a bladder (8) made of an elastic material, the volume of the bladder (8) being variable.

12. The method according to any one of claims 7 to 11, wherein in a first process step the mixture of sealing oil and refrigerant is located in the collection tank (2) and the refrigerant separates from the sealing oil and collects above the sealing oil, wherein the refrigerant located above the sealing oil fills the additional tank (6), wherein in a second process step the collected sealing oil is removed via the discharge (10) and the space above the sealing oil in the collection tank (2) is filled with refrigerant from the additional tank (6).

Images